Create a brushes library/preset and save it (Save Brushes) in the following
C:\Program Files\Adobe\Adobe Photoshop CS5 (64 Bit)\Presets\Brushes\
(I'll check at home for mac)
I removed the pre-existing ones as I never use them.
CS6 allow you to create a button to replace your brushes with a selected one, but I like this technique to keep things clean as my screen workspace is limited.